1. Field of the Invention
The present invention relates to a contactless power transmission device.
Priority is claimed on Japanese Patent Application No. 2011-019443, filed Feb. 1, 2011, and Japanese Patent Application No. 2011-245707, filed Nov. 9, 2011, the content of which is incorporated herein by reference.
2. Description of Related Art
As a charging device for radio communication apparatuses, such as mobile phones, a contactless power transmission device is known.
The contactless power transmission device transmits AC power of a certain frequency from a power transmission device to a power receiving device, which is provided or fixed to a radio communication device, using electromagnetic induction or the like.
For example, U.S Patent Application Publication No. 2008/0001572 discloses a contactless power transmission device mounted in a vehicle.
However, when transmitting electric power in order to charge a radio communication device using a contactless power transmission device mounted in a vehicle, some of the AC power of a frequency used for power transmission or a harmonic or subharmonic of the AC power becomes an electromagnetic wave, an alternating magnetic field, or an alternating electric field and is input as a noise to a neighboring device for a vehicle through the air or a connection cable.
As a result, there has been a problem in that the noise causes degradation of S/N (SN ratio), a reduction in the receiving sensitivity, and the like when a device which transmits or receives information receives the information through radio communication with the outside of the vehicle or radio communication with the inside of the vehicle.
For example, since a harmonic frequency component (for example, approximately 1 MHz in a tenth-order harmonic) in contactless power transmission overlaps an AM radio frequency band (0.5 to 1.6 MHz), it appears as radio noise.
In addition, the harmonic frequency component in contactless power transmission may affect radio communication (one-seg reception or communication with an in-vehicle device using Bluetooth) of a radio communication device being charged.